At the end of his first overseas trip as Secretary of State, John Kerry acknowledged that despite the continued diplomacy and tough sanctions being leveled against Iran, the regime continues to get closer to possessing a nuclear weapon.

"Lines have been drawn before and they've been passed," Kerry said. "That's why the president has been so definitive this time. This is a very challenging moment with great risks and stakes for everybody because the region will be far less stable and far more threatened if Iran were to have a nuclear weapon."

Kerry sat down with ABC News' Martha Raddatz in Qatar as his first overseas trip as President Obama's secretary of state wound down.

Kerry said the threat extends beyond the possibility that Iran could actually use the weapon on its enemies, specifically Israel. Iran simply having a nuclear weapon would "spur a nuclear arms race" in the region and could be used to support terrorists groups like Hezbollah, he said.

The secretary warned that despite last week's negotiations in Almaty between the United States, it's allies and Iran, which he called "useful," time for Iran to cooperate is running out.

"If they keep pushing the limits and not coming with a serious set of proposals or prepared to actually resolve this, obviously the risks get higher and confrontation becomes more possible," he said.

On Syria, the other major focus of this trip, Kerry reiterated that the status quo in the conflict-ridden country is not acceptable. With more than 70,000 people killed over the last two years and recent reports of President Assad al-Bashir using Scud missiles to attack civilian areas, the secretary acknowledged that America must do more.

At a Friends of Syria Meeting in Rome last week Kerry announced the United States would give an additional $60 million in non-lethal aid to Syria's political opposition. The money will be used for communications equipment, training advocates and local governing councils, and to help the opposition deliver services and food to Syrians living in opposition-held areas.

But Kerry also announced that for the first time the United States will be providing non-lethal aid to Syria's military opposition too. For now the help will consist of food and medical supplies, but ABC News learned last week that the aid could eventually include body armor, military training and even tanks.

Kerry would not specifically comment on whether the United States is considering additional aid to the rebel fighters, or on the timing of that decision, but said that it is clear Assad needs to go – and quickly.

"There is a holistic, united effort now that is focused on trying to save lives in Syria, and make it clear to President Assad that we are determined and that he needs to think hard about his calculation in raining Scuds down on his population," said Kerry.

Syria's opposition also has its own problems with extremists elements increasingly playing a role, including carrying out a suicide bombing attack, which killed more than 50 people in Damascus earlier this month. Kerry said that the international community has to be careful about making sure a post-Assad Syria is not substituting one oppressive situation for another.

"I want to emphasize for all of the Alawites who are fearing for their future, for the Christians, or the Druze, or any group there, Sunni, Shiite – they all need to know that the vision of the Syrian opposition, the promise of the Syrian opposition is to have a Syria in which all votes are represented and protected," he said.